The Straight Line as a Roulette

A roulette is the path that a point attached to a circle follows when the circle rolls around another circle. A straight line is a special roulette, when the rolling circle is half as large as the other circle. This phenomenon can be used to convert rotary motion to linear motion.

THINGS TO TRY

SNAPSHOTS

DETAILS

A suggested experiment for Mathematica programmers: make the radius variable, which is now set to in the first line of the program. When you vary the radius, the cylinder (planet) follows a different path. A guide in the shape of the path has to be used to ensure proper operation. A straight guide is used in the basic case.